Output Current Ripple in Electric Vehicles With Asymmetrical Dual Three-Phase Arrangement Applying Interleaved Carrier-Based PWM Techniques

Asymmetrical dual three-phase (ADTP) multiphase arrangements are becoming increasingly important for powertrain applications within the automotive sector. However, further research and development should be carried out in order to improve these arrangements. Lately, there has been a growing interest in exploring enhancements for the pulse-width modulation (PWM) techniques aimed at reducing the current stress of the propulsion system’s DC-Link. In electric vehicle (EV) applications, the voltage-source inverter (VSI) must deliver high power density while meeting stringent reliability requirements. A critical component within the VSI is the DC-Link capacitor, which occupies up to 40% of the inverter volume and contributes to approximately 30% of power converter failures. Reducing the DC-Link ripple current can significantly enhance reliability and reduce system size. However, improvements on the input side often come at the expense of the output side, where excessive current ripple increases Joule losses and induces torque ripple, leading to mechanical vibrations and reduced motor efficiency. Addressing this trade-off is particularly important in ADTP systems, as these configurations are increasingly adopted for high-density, fault-tolerant propulsion systems. In this context, this work evaluates the most relevant carrier-based (CB) PWM techniques regarding the output current ripple quality of an ADTP. For this purpose, a novel method is proposed to calculate the harmonic distortion factor (HDF) of an ADTP arrangement. It is based on the double Fourier integral formalism, instead of the conventional time-domain analysis. The method developed in this work provides accurate harmonic profiles for a thorough comparison among CB-PWMs and enhances the theoretical understanding of how harmonic cancellation works. This innovative approach not only makes the results insensitive to simulation time resolution but also effectively mitigates errors and offsets that arise over the time-domain integration of the voltage measurement. This type of analysis is particularly meaningful when examining the interleaved variations of these CB-PWMs, as they focus on harmonic reduction or cancellation. The experimental validation of this method demonstrates that the results are consistent, providing confidence in the theoretical analysis. In this sense, this work determines how the interleaving schemes, typically used to benefit the DC-Link capacitor, affect the HDF of the ADTP arrangements. Furthermore, this study points out which PWM technique is most promising for ADTP-based propulsion systems, for both improving the performance of the powertrain input (DC side) and its output (AC side, i.e. VSI + electric machine), thus helping engineers and researchers in this field.